Avid Hydraulic disc brake rubbing..how do you adjust?

trtimothy
trtimothy Posts: 117
edited January 2011 in MTB workshop & tech
Hi,

I have a cannondale scalpel with Avid Hydraulic disc brakes. The rear brake is now rubbing on the rotor and I have no idea how to fix it! Is this a job for the bike shop? I've tried looking online for help but as a roadie normally I'm fairly clueless about how to set up hydraulics.

Any help gratefully recieved!

Comments

  • nicklouse
    nicklouse Posts: 50,675
    have a read
    http://www.parktool.com/blog/repair-hel ... and-repair

    could be alignment or you pads need resetting or just bedding in if new.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • trtimothy
    trtimothy Posts: 117
    cheers for that. very helpful website
  • stumpyjon
    stumpyjon Posts: 4,069
    Some rubbing with disks can be inevitable. As long as it doesn't drive you mad and the wheel rotates a few revolutions without stopping when spun it should be OK.

    If not just slacken off the bolts holding the caliper to the fork / frame squeeze and hold the brake lever and gently tighten them back up again (be carefully you can misalign them tightening the bolts). I often align them by eye, bit more fiddly but can sometimes work better. The other thing to check is whether the rotor is dead straight, if it's warped at all it'll be diffiuclt to eliminate all rubbing.
    It's easier to ask for forgiveness than for permission.

    I've bought a new bike....ouch - result
    Can I buy a new bike?...No - no result
  • Anonymous
    Anonymous Posts: 79,667
    Can also be the pistons might need pushing back, especially if you've taken the wheel off at some point and the levers got squeezed or knocked.

    In which case, take the pads out and (ideally with some old knackered pads in place) use a flat bladed screwdriver to push them back. Then put the proper pads back in, fit the wheel and if it's not rubbing, get some card about the thickness of a business card and place two pieces either side of the disc, then apply the brakes in a pumping motion. Remove the card, spin wheel, job done.

    But can be all kinds of other things. Uneven wear (again probably due to pistons or calliper alignment), but only solution there is to replace the pads. Could be the spring clip that holds the pads together is catching on the disc, but you'd get a 'pinging' noise with that. Mud on the pads. Mess about with the Quick Release tightness (if you have QR) as that affects the position of the disc.

    Avids are okay for stopping but they're really frustrating brakes to live with I find.

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